Automatic stack damper



1933- J. E. LUDWIG 1,937,970

AUTOMATIC STACK DAMPER Filed July 7. 1950 INVENTOR Hahn 7. Lirdmi ATTORNEYS Patented Dec. 5, 1933 UNITED STATES" I 2 1,937,970 p, ,HAUTOMATIQ STACK DAMPER John E. Ludwig, Detroit, Mich., assignor to New- I comb-David 00., Inc.',

"ration of Michigan Detroit, Mich., a. corpo- 3 Application July 7, 1930. Serial No. 466,141

'. Y 2 Claims.

The present inventionpertains to a novel automatic stack damper designed for use in connection withspray booths or other spaces from which forcedventilation is required. I

These stacks are ordinarily-used where rapid,

or intensive ventilation isrequired and are made operative by means of ejectors. When the processesv requiring ventilation are stopped, the stacks are often left open or the closing of them is overlooked, as a result of which the idle stacks cause undue and undesired drafts and loss of heat from the building.

The object of the present invention is to overcome this objection and is accomplished by means of a damper which is operated automatically from the blower for supplying the ejector. words, the damper operating device is so related to the air stream produced by the blower that the damper is opened by operation of the blower and automatically closed when the blower is shut down.

A further object of the invention is to provide a compact structure for this purpose. Accordingly, the blower housing is secured directly to the stack and brought into communication with the ejector by means of a suitable spout. Moreover, the motor for driving the blower is supported from the blower housing. These parts are independent of the main damper, except for a driving connection between the damper and an operating member disposed in the stream of the blower. This construction has been found to be simpler, less expensive and more efficient than other devices proposed for the same purpose.

The invention is fully disclosed by way of ex ample in the following description and in the accompanying drawing, in. which Figure 1 is a plan section on the line 1-1 of Figure 2; and

Fig. 2 is a side elevation.

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

In Figure 1 is illustrated a ventilating stack consisting of a number of tubular sections 1 assembled together in a mannerwell known in the art. To one of the sections is secured a substantially cylindrical fan housing 2 having a straight side 3 abutting the section. This side is open, and flanged outwardly at 4 for attachment to the section which in turn is formed with an opening In other zontal, outwardly extending motor base 10. Angular props 11 extend from the outer edge of the member 10 downwardlyto the bars 8 to which they are .secured,for the purpose of rigidly supporting the base 10.

,Upon the base is mounted an electricmotor 12 having a shaft 13 extending through the, opening 6 into the housing 2 whereit carries a fan or impeller 14.

A motor cover is applied over the motor 12 and base 10 and consists of a hood 15 having at one end a flange 16 engaging and secured to one of the lateral walls of the housing 2 outwardly of the angle bars 8. The bottom 17 of the hood is open in order to admit air to the openingfi. Moreover, the end wall of the hood may have a slidable door section 18 movable in guides 19, whereby access to the motor may be had.

From the bottom of the open side of the fan housing 2 extends the bottom 20 of an air spout into the section 1. It will be seen in Figure 2 that the upper wall of the spout has a horizontal portion 21 extending into the section 1 from the highest point of the fan housing and furtherhas an angular portion 22 extending to an ejector or nozzle 23 which is also engaged by the bottom wall 20. The spout is completed by lateral walls 24 as shown more clearly in Figure 1.

At the opening in the section 1 is journalleda shaft 25 carrying a pulley 26 at its free end. At

alower elevation is journalled a parallel shaft 27 1 diametrically of the section 1 and carrying at one end a pulley 28 in line with the member 26. The pulleys are operatively connected together by a belt 29. The shaft 27 carries a circular damper 30 standing in open position in Figure '2 but adapted to obstruct the stack when turned from this position. It will also be seen in Figure 2 that the wall of the section 1 is intact downwardly to the shaft 25 as indicated by the numeral 31. In other words, the lateral opening in the section 1 extends downwardly from the shaft as far as the member 20. The shaft 25 carries a plate 32 adapted to be raised by a stream of air blown from the fan to the nozzle 23..

In the operation of the device, when the blower mined by the elevated position of the plate 32, is such that the damper 30 is held in open position. The stack is rendered inoperative by stopping the fan, in which case the plate 32 drops to its lowest position. The parts are so adjusted that the damper will close when the plate moves to this position. Owing to the closing of the damper the idle stack will not be the cause of undesired drafts and loss of heat therethrough. The air blown by the fan through the ejector 23 is drawn from the atmosphere through the open bottom 17 of the motor cover and into the opening '6. If desired, the cover plate? may be is in motion, the position of the shaft 25, as deterremoved from the opening 5 to admit entrance of air through this opening.

Although a specific embodiment of the invention has been illustrated and described, it will be understood that various alterations in the details of construction may be made Without departing from the scope of the invention, as indicated by the appended claims.

What I claim is: V

1. In combination with a stack having an ejector therein, a fan housing secured directly to said stack, a spout extending from said housing to said ejector and establishing communication therebetween, a motor supported from said housing exteriorly thereof, a fan disposed in said housing and driven by said motor, a cover over said motor and having an open bottom, air inlet means to said to close said stack, said shafts, blade and damper being so related that elevation of the blade opens the damper and dropping of the blade closes the damper.

2. In combination with a stack having an ejector therein, a fan housing secured directly to said stack, a spout extending from said housing to said ejector, said stack having an opening establishing communication between said housing and spout, a motor supported from said housing, a fan disposed in said housing and driven by said motor, a cover over said motor and having an open bottom, air inlet means to said housing at said motor, a shaft jo'urnalled at theupper edge of said opening, a blade on said shaft adapted to be moved by a stream of air delivered by said fan, another shaft journalled in said stack and connectedto the first named shaft, a damper mounted on the second named shaft and adapted to close said stack, said shafts, blade and damper being so related that elevation of the blade opens the damper and drop CERTIFICATE OF CORRECTION.

Patent No. 1,937,970. December 5, 1933.

JOHN E. LUDWIG.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, lines 11 and 81, claim 1 and 2, respectively, for secured directly" read meunted adjacent;

and that the said Letters Patent should be read with these cerrectitms therein that the sarue may conferm to the record ef the case in the Patent ()itice.

Signed and sealed this 15th day of May, A. D. 1934.

Bryan M. Battey (Seal) Acting Qemmissioner 0% Patents, 

